This is a double-blind, randomzied, placebo-controlled, parallel-group, multicenter trial in patients with non-insulin dependent diabetes mellitus (NIDDM). Following a 1-week screening period, patients will discontinue all current pharmacologic treatment for diabetes and enter a 2-week diet therapy baseline study period, after which patients will be randomized in parallel-treatment arms to placebo or troglitazone, 100,200,400 or 600 mg.